The invention relates to a storable and transportable and optionally utilizable mixture containing vegetable residues and at least one polymer product which absorbs water and/or aqueous liquids. The invention also relates to a process for producing said mixture and to the use thereof.
In the utilization of vegetable material, e.g. in the production of vegetable oils, fruit juices, fruit foods, flavors, beer and wine, vegetable residues are obtained in large amounts which are found to be problematic with respect to their further use and disposal. In particular, such disposal is made difficult in that the vegetable material is processed partially with addition of water, so that the largely digested vegetable residues are present as an aqueous mixture which is difficult to handle in terms of transportation, storage or further processing as a result of its inhomogeneous solid/liquid state and biological degradation frequently having begun.
For example, such mixtures are obtained in the production of palm oil or olive oil. M. Hamdi, in Bioprocess Engineering 8 (1993) 209-214, and Garcia-Ortiz Rodrigez et al., in Com. I+D Agroalimentaria 17/95, report on the properties of olive residues, their utility options known to date, and their dumping. Due to their suspension-like state and the rapidly beginning, fermentation-like biological degradation, the transportation and/or storage of these residues is only possible at high cost and with massive impacts on the environment.
According to J. Cegarra et al., Internat. Biodeterioration and Biodegradation (1996), 193-203, the option of using these residues as fertilizers is given only in case of fresh materials or in mixtures with other vegetable waste because of the phytotoxic effects generated during biological degradation.
The same or similar problems also arise with vegetable residues from the production of e.g. fruit juices, fruit foods, flavors, and beer.
It was therefore the object of rendering vegetable residues storable and transportable and optionally, utilizable.
Said object is accomplished by providing a storable and transportable and optionally, utilizable mixture containing vegetable residues, at least one polymer product which absorbs water and/or aqueous liquids, and optionally water.
In the meaning of the invention, transportable indicates that no liquid or virtually no liquid will exude from the mixture of the invention despite the shocks occurring during transportation. In the meaning of the invention, storable indicates that the mixture of the invention does not or only marginally undergo biological degradation over a time period of several weeks.
Optionally, the mixture of the invention may contain water, which water may be process water added to the vegetable material for the processing thereof, cell fluid exuded from the cells, or a mixture of same.
The vegetable residues are roots, stalks, blossoms, leaves and/or preferably fruits of plants, optionally crushed, and in particular, vegetable materials from which preferably at least one constituent has been withdrawn. These constituents can be any constituents in the vegetable material. However, these constituents preferably are vegetable oils, fats, fruit juices, mono-, oligo- and/or polysaccharides and/or odorous substances or flavors.
However, the vegetable residues may also be vegetable wastes such as obtained in industrial processing of field crops such as potatoes, sugar beets, vegetables, as well as fruits, e.g. apples. In particular, when using the mixture according to the invention, storable and transportable and optionally, utilizable materials can be obtained from potato manufacturing residues. Among other things, these residues particularly include potato starch process waste water.
Furthermore, the vegetable residues may also be vegetable materials wherein the process of putrefaction has already begun.
According to the invention, the mixture of the invention includes at least one polymer product in addition to the vegetable residues, which polymer product absorbs water and/or aqueous liquids. Surprisingly, by adding these polymer products to the vegetable residues and the water optionally present, a pasty, fast-drying, solid mass is formed.
It is also surprising that following addition of the polymer product, biological degradation of the vegetable residues does not begin or is interrupted in its course, so that environmental disturbances by harmful degradation products and, in particular, by irritating odors are absent or massively reduced and, in particular, the further use of the mixture according to the invention is not restricted.
In the meaning of the invention, polymer products absorbing water and aqueous liquids are all those polymer products which are referred to as superabsorbers and have been described last by F. L. Buchholz and A. T. Graham, J. Wiley and Sons, New York, 1998, pp. 7 to 17.
Preferably, the polymer products are constituted of
a) 55-99.9 wt.-% of at least one ethylenically unsaturated, polymerizable monomer which contains acid groups and is present as a salt to at least 25 mole-%,
b) 0-40 wt.-% of another ethylenically unsaturated monomer copolymerizable with the monomer according to a),
c) 0.01-5.0 wt.-% of at least one crosslinking agent,
d) 0-30 wt.-% of a water-soluble polymer, the sum of components a)-d) always being 100 wt.-%.
Furthermore, the polymer products additionally may be crosslinked using a subsequent surface treatment, e.g. according to the process specified in DE 40 20 780 C1. The DE 40 20 780 C1 is hereby incorporated by reference and thus, regarded as part of the disclosure.
The polymer products produced according to DE 44 18 818 C2 and DE 42 06 856 C2 are also preferred. These polymer products are characterized by a high absorption capability for water and/or aqueous liquids and by a constant and high absorption rate and distribution, even under pressure, and they are well-known. DE 44 18 818 C2 and DE 42 06 856 C2 are hereby incorporated by reference and thus, regarded as part of the disclosure.
According to the invention, mixtures of various polymer products absorbing water and/or aqueous liquids can be used.
In addition, the mixture of the invention preferably contains natural and/or modified polysaccharides. Such natural and/or modified polysaccharides are cellulose, starch, cellulose ethers such as carboxymethylcellulose, methylcellulose, methylhydroxyalkylcellulose, hydroxyethylcellulose, ethylcellulose, ethylhydroxyethylcellulose, hydroxypropylcellulose, as well as carboxymethylhydroxyethylcellulose and/or oxidized, anionic starches and anionic starch ethers.
Advantageously, the mixture of the invention is produced by adding the optionally crushed vegetable residues and the water optionally present with at least one polymer product which absorbs water and/or aqueous liquids. Therefore, the invention is also directed to this process according to the invention.
The polymer products preferably are added as powders having a grain size distribution ranging from 10 to 10,000 xcexcm, preferably from 10 to 5,000 xcexcm, and more preferably from 10 to 3,500 xcexcm, and particularly as polymer fines and/or as a water-in-oil dispersion. Also, polymer products having a grain size of less than 200 xcexcm are well-suited, and particularly suitable are polymer particles having a grain size distribution between 10 and 150 xcexcm.
The polymer product is added in such an amount that the mixture of the invention is present as a solid or a cut-resistant mass. It is also preferred to add the polymer product in such an amount that the mixture of the invention after a maximum of 15 minutes is present as a pasty, fast-drying mass and more preferably, however, as a crumbly solid. Relative to the mixture of vegetable residue and water optionally present, the polymer product preferably is added in an amount of from 0.1 to 10.0 wt.-%, more preferably from 0.2 to 5.0 wt.-%, with a range of from 0.25 to 2.5 wt.-% being particularly preferred.
If the vegetable material is to be crushed, the polymer product preferably is added during said crushing. It is also preferred to meter the polymer product prior to, during and/or after removal of one or more constituents from the vegetable material. Addition may also be effected in partial amounts and at various sites of the production process.
Advantageously, the polymer product is metered into the vegetable residues during their conveyance from the respective plant into e.g. a container or a truck, using a screw, for example.
Containing considerable amounts of substances useful for growing plants, such as potassium salts and phosphates, the mixture of the invention can be used as soil improver and/or fertilizer and/or as component in a fertilizer, and as an artificial soil substrate in plant breeding.
On the one hand, when producing the mixtures according to the invention using process waste waters from starch extraction from potatoes, environmentally adverse malodors are avoided and, on the other hand, when using the mixture as fertilizer or fertilizer component, there is a delayed release of compounds containing potassium and nitrogen, so that the disadvantages of direct, fertilizing irrigation are avoided.
In addition, dumping or combustion of the mixture according to the invention is possible without problems.
Furthermore, the mixture of the invention is suitable as an intermediate in the isolation of other constituents or plant components, e.g. by extraction using organic, water-miscible and/or water-insoluble solvents such as n- and/or isoalkanols such as methanol, ethanol and isopropyl alcohol, liquid n- and/or isoalkanes and aromatic hydrocarbons such as n-hexane, cyclohexane or benzene, or by means of steam distillation. For example, these constituents are phenolic compounds such as tyrosol, hydroxytyrosol, oleuropein, caffeic acid, vanillic acid, syringic acid, p-coumarin, o-coumarin, protocatechuic acid, p-hydroxybenzoic acid, and homovanillic acid.
Also, the mixture of the invention is used as raw material in the isolation of other products such as polysaccharides, e.g. in the production of xanthan gum.
Therefore, the present invention is also directed to the above-mentioned uses.